To be sure, they are very different entities. Most importantly, Twitter Inc. is a publicly traded company, while the Wikimedia Foundation is a non-profit organization. But both are important platforms in the online information ecosystem facing significant questions about not just its future but even its present. Both have much in common in their history and structure, and in the challenges they now face:

Wikipedia and Twitter both started out as side projects of other projects that weren’t going anywhere: Wikipedia of traditionally-edited online encyclopedia Nupedia, and Twitter of possibly-before-its-time podcast directory Odeo.

Both are basically monopolies in their particular corner of the information ecosystem: Wikipedia has no competitor in collating the “sum of all human knowledge” into readable text; Twitter is the only public, real-time conversation network (in perhaps this alone it has bested Facebook). Both have been described as a “utility” at one time or another.

Both are among the most-recognized, heavily-visited destinations on the web. Google pretty much points searchers to Wikipedia by default, and recently re-upped a deal to provide Twitter results in searches. Both are top 10 global websites: according to Alexa, Wikipedia is 7th and Twitter is 10th. In the U.S., Wikipedia is currently 6th and Twitter 8th.

Both are open publishing platforms, inviting its readers to be contributors. Even so, the vast majority of participants (broadly defined) choose only to consume. Wikipedia’s reader base has always vastly exceeded its editors, which isn’t a huge surprise. But Twitter has been trending this way for a number of years. (See also: the Pareto principle, the Internet’s 1% rule).

One possible reason why both have so few active contributors is that they are both notoriously difficult to use. This is rather obviously true for Wikipedia. It is, after all, an encyclopedia, and making beneficial contributions to it requires time, knowledge and inclination (not to mention persistence and thick skin). Twitter’s 140-character simplicity belies its true complexity, as Walt Mossberg has argued recently.

Both are organized as democratic, non-hierarchical platforms where everyone theoretically has an equal chance to be seen and heard. But of course invisible hierarchies emerge, as certain power users self-identify through the strength of social ties or canny dexterity with the platform. Twitter at least makes follower counts public, while Wikipedia is considerably more opaque.

For each, active users grew dramatically (even exponentially) until hitting a peak and then declining. This happened for Wikipedia in 2007, which happened to be the same year Twitter first started gaining traction. However, this growth ran out by 2009, making for a very similar looking user growth-and-decline charts:

Both allow users anonymity—or, more accurately, pseudonymity—which arguably fosters a community culture suffering from a lack of responsibility and accountability. Relatedly, both have had significant trouble with the so-called Gamergate movement, and female users of both platforms have reported serious harassment issues.

Fallings out among top leadership have been the norm since the beginning. At Wikipedia, co-founder Larry Sanger became disillusioned with the project, leaving Jimmy Wales free to bask in the glory of being a “digital god” as the Evening Standard actually called him last week. As Nick Bilton described in his book, Hatching Twitter, Twitter’s most contentious co-founders, Jack Dorsey and Ev Williams, were at each other’s throats almost constantly. Multiple defenestrations later, Dorsey once again leads the company as CEO.

Besides the personal squabbles among its founders, both have experienced very recent and very concerning internal confusion at the company / parent organization, riven with conflicts about the future of the organization, and a revolving door of high-level executives. For Twitter, this has been in the tech press almost constantly. For Wikipedia, this has been covered most extensively by only The Wikipedia Signpost and a handful of blogs, including this one.

The direction of each has caused immense consternation in the community of power users who are conflicted about revisions to the platform, both rumored and launched. Impending changes to Twitter’s character limit and algorithmic order of tweets can be compared to community revolts over several recent software initiatives, especially the Visual Editor debacle, which sought to fundamentally change the nature of editors’ interaction with the site. At present, Wikipedians are anxious to know if this “Knowledge Engine” project is another.

For both, the silver lining is that their position is secure so long as arguments are being had there: that people care about what is being said on each website. No matter what ails each one, no competitor is likely to displace them, and their core function is likely to be relevant for the foreseeable future.

Are there lessons for one or the other? I’m not so sure. One conclusion that does occur to me as a longtime Wikipedia editor, observer and fan: how fortunate is Wikipedia to be a non-profit foundation right now! Whatever complaints one may have about Jimmy Wales, and there are many valid ones, his decision to forsake the chance to become “an Internet billionaire” on the back of Wikipedia, as The New York Times once put it, infelicitously, owes significantly to its central role on the Internet today. Had, for example, Wales insisted on monetizing Wikipedia with advertising (something Twitter once, long ago, promised it would never do, and only recently has begun turning off ads for power users) the rest of Wikipedia’s contributors might have walked out the door along with the 2002 “Spanish fork”.

Twitter, on the other hand, was founded by startup veterans who probably never seriously considered doing anything but become Internet billionaires. (For what it’s worth, Dorsey and Williams both achieved this goal.) I come here not to criticize the ambition, but to observe that it hasn’t worked out so well for the platform. In its attempts to generate revenue to match their brand recognition, Twitter has experimented with several different strategies and business models. Unfortunately, these often ran at cross-purposes to what Twitter was good at, as observers from Ben Thompson to Twitter investor Chris Sacca have both written. That it is now publicly traded is a worse headache, and places on it a burden of expectations that may ultimately spell its doom as an independent company.

Fortunately for Wikipedia, it has a clearer notion of what it should be. It is an encyclopedia. Its recent struggles may owe something to the fact that the Wikimedia Foundation doesn’t always seem to recognize that. Twitter may have largely succeed at becoming “the pulse of the planet” but, for a company whose shareholders expect continuing growth, that isn’t enough.

In three postslast week, I considered how buzzy Q&A website Quora is more like Wikipedia than not. In this post, I’ll address how the different organizations behind them may affect the communities surrounding each.

For all of Quora’s upbeat talk about wanting to become “the best place” for answering questions on any conceivable topic, it is first and foremost a for-profit enterprise, and one allegedly worth somewhere between $300 million and $1 billion. It’s not hard to imagine how outside pressures (such as those from investors) might eventually force Quora to choose between the best thing for its community’s experience and the best thing for its financial well-being.

In fact, this probably has already discouraged one type of editor: the free culture / free software crowd, who helped build Wikipedia. One would think these folks might otherwise be interested in building a universal repository of information—but not if it’s a closed system. As we’ve seen in the unhapphiness of some Huffington Post bloggers following that site’s sale to AOL, one needn’t be a close follower of Richard Stallman to have questions about spending a lot of time helping to build a resource that may never produce a monetary return. Now, I am not saying those complaining about HuffPo are right, or discounting that participation on such platforms can be rewarding for non-monetary reasons. But it’s something Quora will have to look out for.

A good example involves an incident well-known at Wikipedia where, in the site’s early years, a significant number of editors on Wikipedia’s nascent Spanish-language edition decamped over such concerns. Among several reasons for the split, the most significant involved a suggestion (not even a real proposal) that Wikipedia would pay the bills by selling ads on the website. At the time, Wikipedia belonged to a private company owned by Jimmy Wales, and its url was www.wikipedia.com. So they left and started a competitor, Enciclopedia Libre Universal. The Spanish-language Wikipedia eventually recovered and outpaced its rival, but not for several years. (Wikipedians call this the “Spanish Fork”; for more information see this Jauary 2011 interview and Andrew Lih’s book, The Wikipedia Revolution.)

It probably doesn’t matter whether Quora might one day include advertising, because these types of editors would never have showed up in the first place. Let’s imagine, just for the moment, that they did open up advertising. One way or another, that would end up influencing content, which would be hard to reconcile with their stated goal that “each question page become the best possible resource for someone who wants to know about the question.” Even if advertising didn’t influence content, it would inevitably interfere with it.

A handy comparison is Twitter: a few years back, one of it co-founders inadvisably pledged the site would “never” have advertising. They came up with a clever solution in Promoted Tweets, but there are still backlashes in store, like the one this past weekend over the “quickbar” added to Twitter’s iPhone app. And remember, the question here is not whether Quora will alienate participants so much they all leave—but whether enough disengage or never show up to keep it from competing with Wikipedia for mindshare in a serious way.

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Of course, it must be acknowledged that Wikipedia’s being a non-profit foundation (taking over for Wales’ dot com in 2003) comes with its own drawbacks. Late last year, many readers expressed displeasure with the months-long banner campaign featuring Wales and others “begging” for money. But they say this about NPR, too. And while its listeners put up with it (even as they sometimes put in for it) there is a huge audience of people who like neither the content nor the management, and stay away.

One thing about being a hot new startup does help Quora: it has a dedicated design team actively working on the site design, and can make decisions more quickly. Wikipedia often struggles to make big changes, and with implementation of Flagged revisions or the debate over paid editing, disagreement can lead to paralysis and a default to the status quo.

At the moment, which is better remains a philosophical question: Wikipedia’s open and free nature vs. Quora’s closed and proprietary model. If you think that sounds like an easy question, consider the debate between Apple’s iOS and Google’s Android. The two operating systems are currently very competitive, and it’s an open question which will pull ahead. Applications within Apple’s closely-regulated App Store are far more reliable and considered to be of higher quality than those within Google’s open app marketplace.

For any number of reasons, this may not be a great analogy for discussing Wikipedia and Quora. But consider how competitive the Android platform might be if it had debuted not one year after Apple’s iPhone but ten years. If Quora had launched at the beginning of the 2000s instead of its end, we might be talking about a very different competition. Right now, it is difficult to see how Quora can close the gap (more like a vast gulf) between itself and Wikipedia. At least, it won’t happen anytime soon.

But perhaps the Wikipedia comparison is setting the bar too high. Quora is an interesting platform, and I don’t see why it needs to achieve a Wikipedia-like ubiquity to become useful. It certainly needs to displace Yahoo! Answers, and it needs to start showing up in Google search results. If its community continues to grow and build out its content in areas that Wikipedia doesn’t want to cover, then it just might have a chance. The philosophical difference is resolvable only with data: as Quora develops in months and years to come, we’ll see how it stacks up. I’ll still be spending most of my time on Wikipedia, both as a reader and an editor. But if I can’t find it there, my next stop will definitely be Quora.